Process for preparing alkylated aromatic compounds



United States Patent 3,363,018 PROCESS FOR PREPARING ALKYLATED AROMATIC COIWPOUNDS Joseph A. Cahili, Philadelphia, Robert M. Lincoln, Moylan, Joseph A. Meyers, Springfield, and Harold Shalit, Drexel Hill, Pa., assignors to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Filed June 17, 1965, Ser. No. 464,830

. 6 Claims. (Cl. 260-671) ABSTRACT OF THE DISCLOSURE This invention relates to an improvement in the method of preparing alkylbenzene using Type III olefins containing from to 16 carbon atoms which comprises isomerizing the olefins to shift the terminal double bond to an internal position thereby substantially reducing dimerization during the alkylation. This isomerization substantially increases the yield of alkylate having a 10 to 16 carbon side chain.

This invention relates to a process for preparing alkylated aromatic compounds and more particularly to an improved process for preparing alkylated aromatic compounds Which may be utilized to prepare alkylaryl sulfonate detergents.

It is known to alkylate benzene or other low molecular weight aromatic compounds of the benzene series such as for example, toluene, xylene, cumene, and the like with a C -C Type III olefin in the presence of an acidic catalyst including the Bronsted acids such as for example H 50 HF, etc. and the Lewis acids such as for example AlCl AlBr Fecl etc. to obtain alkylated aromatic compounds containing 10 to 16 carbon atoms in the alkyl side chain. Excellent detergents are obtained when these alkylated aromatic compounds are sulfonated and the thereby obtained sulfonic acids are neutralized with a salt forming base such as for example, sodium hydroxide to form the water soluble alkylaryl sulfonate detergent.

Unfortunately the aforementioned alkylation reaction does not produce a high yield of the desired alkylated aromatic compounds, i.e., those containing 10 to 16 carbon atoms in the alkyl side chain. After extensive research, it has been found that a relatively high proportion of the C -C Type III olefins under the alkylation conditions unexpectedly dirnerize prior to alkylation thereby forming substantial amounts of undesirable alkylated aromatic compounds wherein the alkyl side chain contains greater than 16 carbon atoms. It can be appreciated that any of the C C Type III olefins which dimerize prior to alkylation reduce the yield of alkylated aromatic compounds having 10 to 16 carbon atoms in the alkyl side chain.

It is therefore an object of this invention to provide a process for preparing in improved yields C -C alkylated aromatic compounds.

It is another object of this invention to provide a process for improving the yield of alkylated aromatic compounds having 10 to 16 carbon atoms in the alkyl side chain prepared by reacting an aromatic compound with a C -C Type III olefin in the presence of an alkylation catalyst wherein at least a portion of the Type III olefin dimerizes prior to alkylation.

Generally speaking and in accordance with the above objects and their attendant advantages, it has been found that by catalytically isomerizing C -C Type III olefins to shift the terminal double bond of the Type III olefins to an internal position prior to alkylating the aromatic compounds there are obtained improved yields of C -C alkylated aromatic compounds. More specifically this invention comprises an improvement in the process for preparing C -C alkylated aromatic compounds from a Type III olefin of the formula wherein R and R each are alkyl radicals having 1 to 10 carbon atoms, wherein the sum of the carbon atoms in R and R is in the range of 8 to 14 and wherein the Type III olefins are reacted with a low molecular weight aromatic compound of the benzene series in the presence of an acidic alkylation catalyst, wherein at least a portion of the Type III olefins dimerize prior to alkylation by catalytically isomerizing the Type III olefins to shift the terminal double bond to an internal position, and alkylating the aromatic compound with this isomerized product in the presence of the alkylation catalyst to produce the desired alkylated aromatic compounds. A preferred mode of practicing this invention comprises catalytically isomerizing a straight chain Type III olefin as defined above to shift the double bond to an internal position in the presence of silica alumina at temperatures ranging from about 50 C. to about C. wherein the silica alumina is present in an amount ranging from about 5 to about 10 weight percent based on the Weight of the Type III olefin and alkylating benzene with the isomerized Type IE olefin in the presence of aluminum chloride alkylation catalyst.

The Type III olefins suitable for use in the practice of this invention and hereinafter referred to as C -C Type III olefins are characterized by the formula:

wherein R and R each are alkyl radicals having one to 10 carbon atoms and wherein the sum of the carbon atoms in R and R is in the range of 8 to 14. Individual olefins or a mixture of olefins may be utilized. The alkyl radicals may be straight or branched chain. Preferably C C Type III olefins wherein R and R are straight or substantially straight chain are utilized because alkylaryl sulfonate detergents prepared therefrom are more susceptible to bacterial degradation than the corresponding detergents prepared from C -C Type III olefins wherein R and R are branched.

The C -C Type III olefins may be prepared in a variety of Ways. For example, they may be prepared by the dehydrohalogenation of 2,2-dialkyl-1-halo ethane having the same carbon number as that of the desired olefin. They also may be prepared by the dehydration of a 2,2-dialkyll-hydroxy ethane having the same carbon number as that of the desired olefins or by pyrolysis of the acetate of the aforementioned alcohol. In addition, they may be prepared by reacting a ketone having a carbon number one less than that of the desired olefin with triphenylphosphine methylene according to the Wittig Reaction. All of 3 the above methods are documented in the literature and are well known to those skilled in the art.

A particularly desirable method for preparing C -C Type III olefins wherein R and R, as previously defined, are straight chain is by dimerizing lower molecular weight straight chain alpha olefins. For example a straight chain alpha olefin containing 5 to 8 carbon atoms in the molecule or mixtures of these olefins can be dimerized to produce C C Type III olefins. Also, C -C Type III olefins can be prepared by codimerizing propylene with a C C C or C straight chain alpha olefin or with mixtures thereof or by codimerizing butene-l with a C C C C straight chain alpha olefin or with mixtures thereof. The dimerization reaction is carried out in the presence of an organo-aluminum catalyst of the so-called Ziegler type such as for example, trialkyl aluminum, aluminum trihydrocarbyl, lithium aluminum hydride and the like at temperatures ranging from 80 C. to 310 C. and preferably in the range of 115 C. to 250 C. and at pressures ranging from atmospheric to 200 atmospheres and preferably atmospheric. The dimerization product in addition to containing C -C olefins also will contain small amounts of unreacted lower molecular weight olefins and higher molecular weight olefins which can be conveniently separated from the reaction mixture by fractionation. The C -C olefins will be comprised of a mixture of olefins of which the major proportion is the Type III olefin, i.e. about 80 to 90 volume percent with smaller amounts of Type II, Type IV, and Type V olefins also present. It is unnecessary to separate the Type III olefins from the mixture prior to isomerization. Alkylaryl sulfonates prepared in accordance with this invention from C C Type III olefins which are derived by the above dimerization reaction have in addition to good detergent properties, excellent biodegradable properties.

In the practice of this invention, the C C Type III olefins are catalytic-ally isomerized in the presence of any suitable catalyst that will cause the terminal double bond to shift to an internal position. Such catalysts are well known in the art. For example, the terminal bond of the Type III olefin may be isomerized to an internal position in the presence of 70 weight percent sulfuric acid at temperatures ranging from room temperature to about 100 C. and preferably at room temperature. The isomerization also may be effected by concentrated hydrochloric acid at temperatures ranging from about 100 C. to about 200 C. and preferably at about 150 C. Another suitable isomerization catalyst is silica gel impregnated with about 40 percent sulfuric acid. The isomerization in the presence of this catalyst may be accomplished at temperatures ranging from about 50 C. to 200 C. and preferably at about 90 C. Other effective isomerization catalysts suitable for the practice of this invention include silica gel, activated clay, phosphoric acid on pumice, and chromium oxide. The isomerization reaction utilizing any of these catalysts is conducted at temperatures ranging from about 150 C. to about 300 C. and preferably about 200 C. After the isomerization reaction is complete, the catalyst is separated from the reaction mixture in any suitable way. For instance when the isomerization catalyst is a liquid, e.g. H 50 the reaction mixture may be water washed to remove the catalyst. On the other hand, when the isomerization catalyst is a solid, e.g. activated clay, the catalyst may be removed by filtration.

Preferably, isomerization of the terminal double bond of the C -C Type III olefin is accomplished in the presence of silica alumina at temperatures ranging from about room temperature to about 200 C. and most preferably at temperatures ranging from about 50 C. to about 100 C. The silica alumina catalyst should be present in an amount ranging from about 1 to about 20 weight percent based on the weight of olefin charged and preferably in an amount ranging from about 5 to about 10 weight percent based on the weight of olefin charged. The isomerization reaction should be allowed to proceed until analysis of a portion of the reaction mixture, as by infra red analysis, indicates that the Type III olefins have been converted or substantially converted to olefins with an internal bond. After the isomerization reaction is complete, the silica alumina may be conveniently separated from the reaction mixture by filtration.

The isomerized C -C Type III olefin is then utilized to alkylate benzene or other low molecular weight aromatic compound of the benzene series such as for example, toluene, any one or a mixture of the isomeric xylenes, n-propyl benzene, diethyl benzene, and the like, including alkyl benzenes wherein the 'alkyl group contains from 1 to 3 carbon atoms with preferably no more than 2 such groups on the benzene ring. It is preferred that benzene be alkylated With the isomerized C -C Type III olefin.

The alkylation reaction may be carried out in any suitable known manner in the presence of an acid catalyst such as for example, H HF, A1Br FeCl and the like at temperatures ranging between 0 C. and C. with the most desirable temperature range being between 40 C. and 60 C. When a metal halide catalyst is used, it should be present in concentrations ranging from about 0.1 to about 10 weight percent based on the weight of aromatic present. On the other hand, when a Brgzinsted acid catalyst is used, it is necessary that it be present in higher concentrations, e.g. at least 10 weight percent for H 80 and about 100 mole percent for HP.

The alkylation is preferably accomplished in the presence of AlCl at temperatures ranging between 0 C. and 100C. and most preferably between 40 C. and 60 C. and in concentrations between about 0.1 and about 10 weight percent and most preferably between about 0.5 and about 2 weight percent based on the amount of aromatic present. The AlCl is added in the form of a slurry of conventional liquid aluminum chloride complex, for example, a complex of aluminum'cholride with the alkylate produced or a complex with an aromatic hydrocarbon, e.g. benzene. The aluminum chloride will normally comprise from about 30 Weight percent to 45 weight percent of the slurry.

Excellent detergents can be prepared by sulfonating the alkylated aromatic compound utilizing concentrated sulfuric acid, S0 or oleum and neutralizing the resulting sulfonic acids with a salt forming base such as for example, NaOH according to any one of the well-known R-OHz-CHa Aromatic Compound C=OHa Acid R Catalyst RCH2CHZB RCH3CH2 C-OHa On the other hand it has been found that if the terminal bond of the Type III olefin is isomerized to an internal position, olefin dimerization is precluded so that the principal alkylate produced is alkylbenzenes having 10 to 16 lows:

RCH2CH2 isomerization /C=CH2 R t CH -C-CH2CH2-R R CH2CH alkylation C-CH;

and other isomers and other isomers It should be understood that the above explanation should in no way be construed to limit the invention as claimed.

In order that those skilled in the art may better understand how the present invention may be practiced, the following examples are given by way of illustration and not by way of limitation. The first four examples are illustrative of alkylbenzenes prepared from Type II olefins that were not isomerized prior to alkylation whereas Examples 5 to are illustrative of alkylbenzenes prepared from Type IH olefins that were isomerized prior to alkylation. For ease of comparison, the yields obtained in each of the examples are summarized in Table I. To further show the eflectiveness of isomerizing the Type III olefins, there is also included in Table I a heart out to bottoms ratio. This ratio was obtained by comparing the amount of detergent range alkylate, i.e. those containing 10 to 16 carbon atoms in the alkyl side chain with the amount of higher molecular weight alkylbenzenes and other undesirable higher molecular weight products produced during the alkylation reaction. The higher the heart cut to bottoms ratio, the higher the conversion of the Type III olefins to detergent range alkylbenzenes. The Type III olefins utilized in each of the examples were prepared by dimerizing lower molecular weight olefins as hereinabove described. The isomerization catalyst utilized in each of the examples was a commercial synthetic silica alumina cracking catalyst comprised of 88 weight percent silica and 12 weight percent alumina. The alkylation catalyst utilized in each of the examples was conventional A101 slurry consisting of a complex of AlCl and alkylated benzene and comprised of 35.2 weight percent active AlCl Example 1 There were added to a round bottom flask fitted with a dropping funnel, mechanical stirrer and water condenser, 120 milliliters of benzene and 4 milliliters of aluminum chloride slurry. The contents of the flask were heated to 50 C. and maintained at this temperature as 30 milliliters of a mixture of C -C Type III olefins boiling between 180 C. and 235 C. were added dropwise over a 15 minute period. After addition of the olefin, the contents of the flask were maintained at 50 C. for an additional 15 minutes to insure complete reaction. The reaction mixture then was washed with a 5 weight percent solution of NaOH, dried over magnesium sulfate and stripped free of unreacted benzene. The remaining product was then vacuum distilled and there were recovered 1.3 grams of forerun 1 boiling between 182 C. and 220 C., 17.6 grams of C -C alkylbenzenes boiling between 265 C. and 310 C. and 9.2 grams of bottoms.

Example 2 The reactants and amounts thereof and the alkylating procedure set forth in Example 1 was exactly followed except that 6 milliliters of AlCl slurry were used instead of 4 milliliters. Upon vacuum distilling the reaction product there were recovered 2.6 grams of forerun boiling between 185 C. and 220 C., 16.7 grams of C -C 1 The forerun obtained in each of the examples is comprised mainly of unreacted olefins.

6 alkylbenzenes boiling between 260 C. and 310 C. and 10 grams of bottoms.

Example 3 There were added to a round bottom flask 150 milliliters o-f benzene. HCl gas Was bubbled through the benzene for 15 minutes at room temperature. The contents of the flask then were heated to 50 C. and 1.6 milliliters of A101 slurry were added. While the temperature of the reaction mixture was maintained at 50 C., a C Type III olefin boiling between 210 C. and 215 C. and additional AlCl slurry were added to the flask as follows:

(a) 10 milliliters of C Type III olefin over a 15- minute period (b) 0.3 milliliter of A1Cl slurry (-c) 10 milliliters of C Type III olefin over a 15- minute period (d) 0.5 milliliters of A1Cl slurry (e) 10 milliliters of C Type HI olefin over a 15- minute period.

The contents of the flask were then stirred for an additional 15 minutes period while maintaining the temperature at 50 C. to insure complete reaction. The reaction mixture then was washed with a 5 Weight percent solution of NaOH, dried over magnesium sulfate and stripped free of unreacted benzene. The remaining product was then vacuum distilled and there were recovered 0.9 gram of forerun boiling up to 220 C., 18.4 grams of C alkylbenzenes having a boiling point of about 310 C., and 8.3 grams of bottoms.

Example4 There were added to a round bottom flask fitted with a dropping funnel, mechanical stirrer and water condenser 240 milliliters of benzene and 4 milliliters of A101 slurry. The contents of the flask were heated to 50 C. and maintained at this temperature as 60 milliliters of a C Type III olefin having a boiling point of 234 C. was added dropwise over a 15 minute period. After addition of the olefin, the contents of the flask were maintained at 50 C. for 15 more minutes to insure complete reaction. The reaction mixture then was washed with a 6 weight percent solution of NaOH, dried over magnesium sulfate and stripped free of unreacted benzene. The remaining product was then vacuum distilled and there were recovered 0.75 gram of forerun boiling up to 250 C., 29.9 grams of a C alkylbenzene boiling between 300 C. and 340 C., and 26.2 grams of bottoms.

Example 5 To isomerize a C Type III olefin having a boiling point of about 205 C., 225 grams of the olefin were isomerized in the presence of 11.3 grams of silica alumina in a flask fitted with a thermometer, mechanical stirrer, and water condenser. This reaction mixture was heated to C. for one hour. The silica alumina was removed from the isomerized olefin by filtration. To prepare the alkylbenzene, 168 grams of the isomerized olefin were added dropwise over a 30 minute period to a round bottom flask which was fitted with a mechanical stirrer, water condenser, and dropping funnel and which contained 900 milliliters of benzene and 15 milliliters of AlCl slurry. The temperature of the reaction mixture was maintained at 50 C. After addition of the isomerized olefin, the temperature of the reaction mixture was maintained at 50 C. for an additional 15 minutes to insure complete reaction. After washing, drying and stripping the reaction product as described in Example 1, the reaction product was distilled and there were obtained 10 grams of forerun boiling between 210 C. and 216 C., 201.8 grams of C alkylbenzenes boiling between 285 C. and 330 C., and 22.2 grams of bottoms.

Example 6 A ZO-gram portion of the isomerized olefin prepared in Example 5 was distilled and there were obtained 18.7

grams of a C olefin having a boiling point of about '205 C. and 1 gram of bottoms. According to the method Example 7 According essentially to the procedure set forth in Example 5, 32 milliliters of a mixture of C -C Type III olefins rboiling between 182 C. and 250 C. were isomerized at 50 C. in the presence of 1.5 grams of silica alumina. The reaction was terminated when infra red analysis of a portion of the reaction mixture indicated that the isomerization was complete. (The disappearance of the Type HI olefin was followed by reduction in intensity of the 11.3 micron band.) According to the procedure set forth in Example 1, 120 milliliters of benzene were alkylated with 21 grams of the isomerized olefin in the presence of 2 milliliters of AlCl slurry. Upon vacuum distilling the reaction product, there were obtained 2.1 grams of forerun boiling between 215 C. and 270 C., 21 :grams of C -C alkylbenzenes boiling between 275 C. and 360 C., and 2.6 grams of bottoms.

Example 8 According essentially to the procedure set forth in Example 5, 32 milliliters of a mixture of C -C Type III olefins boiling between 170 C. and 258 C. were isomerized at 50 C. in the presence of 1.5 grams of silica alumina. The reaction was terminated when infra red analysis of the reaction mixture indicated that the isomerization was complete. According to the procedure set forth in Example 1, 120 milliliters of benzene were alkylated with 18.8 grams of the isomerized olefin in the presence of 2 milliliters of AlCl slurry. Upon vacuum distillation of the reaction product there were obtained 1.3 grams of forerun boiling between 205 C. and 250 C., 20.1 grams of C -C alkylbenzene boiling between 285 C. and 340 C., and 2.8 grams of bottoms.

Example 9 According essentially to the procedure set forth in Example 5, 30 milliliters of a mixture of C C Type III olefins boiling between 190 C. and 245 C. were isomerized for 15 minutes at 50 C. in the presence of 1 grams of silica alumina. All of the isomerized olefin was used to alkylate 120 milliliters of benzene in the presence of 4 milliliters of AlCl slurry according to the procedure set forth in Example 1. Upon vacuum distilling the reaction product, there were obtained 0.8 gram of forerun boiling between 175 C. and 255 C., 26.0 grams of C C .alkylbenzenes boiling between 255 C. and 330 C.. and 4.4 grams of bottoms.

Example According essentially to the procedure set forth in Example 5, 54 milliliters of a C Type III olefin having a boiling point of 234 C. were isomerized at 50 C. in the presence of 1.5 grams of silica alumina. The reaction was terminated when infra red analysis of a portion of the reaction mixture indicated that the isomerization was complete. According essentially to the procedure set forth in Example 1, 240 milliliters of benzene were alkylated with 54 milliliters of above isomerized olefin in the presence of 4 milliliters of AlCl slurry. Upon vacuum distillation of the reaction product there were obtained 1.7 grams of forerun boiling up to 250 C., 45 grams of C alkylbenzenes boiling between 325 C. and 340 C., and 7.7 grams of bottoms.

TABLE I Wt. percent of theoretical yield of Heart cut Example No. detergent range alkylto bottoms benzenes based on ratio olefins charged Unisomerized:

It can be seen clearly from Table I that Type III olefins which are not isomerized prior to alkylation (Examples 1 to 4) produce a lower yield of the desired alkylbenzenes when reacted with benzene in the presence of AlCl than when the Type III olefin is isomerized prior to alkylation (Examples 5 to 10). When the heart out to bottoms ratio of the alkylbenzenes prepared from the unisomerized Type III olefins (Examples 1 to 4) is compared with the corresponding ratio of alkylbenzenes prepared from the isomerized Type III olefins (Examples 5 to 10) it is evident that the isomerization step precludes the formation of higher molecular Weight products,'i.e., the bottoms, and the formation of the desired alkylbenzenes, i.e., the heart out is maximized.

As previously stated, it is preferred in the practice of this invention that the C -C Type III olefins utilized be those in which the alkyl chains connected to the carbon atom adjacent the terminal carbon atom are straight chain, i.e., R and R as hereinabove defined are straight or relatively straight chain. It has been found unexpectedly that alkylaryl sulfonates prepared from the isomerized product of these olefins are as susceptible as, and in some instances more susceptible to bacteriological degradation than alkylaryl sulfonates prepared from the unisomerized Type III olefins, Data included in Table II below shows the biodegradable properties of sodium alkylbenzene sulfonates prepared by sulfonating and neutralizing the alkylated benzenes of the examples, The sodium alkylbenzene sulfonates were prepared according to the following procedure. There were added dropwise l0 milliliters of 20 percent fuming sulfuric acid to a round bottom flask containing 10 milliliters of the alkylated benzenes prepared in the above examples. The acid was added to the alkylated benzene over a 30 minute period with vi orous agitation of the reaction mixture which was maintained at a temperature of from 35 C. to 40 C. After all of the acid had been added, the reaction mixture was stirred for an additional 30 minutes to insure complete sulfonation of the alkylated benzenes. The reaction mixture was then transferred to a separatory funnel where spent acid was removed. The remaining upper layer was neutralized with 10 weight percent NaOH. Sufiicient benzene, alcohol and water were added to separate the neutralized sulfonic acids from the unreacted hydrocarbons. The lower layer which formed was evaporated to obtain the sodium alkylbenzene sulfonate which was then desalted by extractionwith an aqueous-isobutanol solution.

The sodium alkylbenzene sulfonates were then tested to evaluate their bacteriological degradation properties. In this test, natural, raw river water having a normal bacteria population is utilized. A sufiicient quantity of the detergent is added to the river water to make up a solution containing about 5 parts per million of the detergent. The solution is tested immediately for its detergent content by the methylene blue method as described in Standard Methods for the Examination of Water and Wastewater, American Public Health Association, Inc., New York, N.Y. (1960), pages 246248. Each solution is tested periodically to determine the amount of detergent that has not been degraded by the bacteria. This amount is corrected by subtracting therefrom the trace amount of detergent that is present in the raw river water as calculated by running the same methylene blue test on a sample of raw river water to which no detergent has been added.

5 The results of the tests are reported in Table II below. zene by TABLE II Amount of Sodium Alkylbenzeue Sulfonate Remaining in Solution in Parts per Million D ays 1 2 3 4 5 6 7 8 9 10 12 14 21 22 28 30 Sodium Alkylbenzene Sultanate Prepared from the Alkylated Benzene of:

Example 10. ...i

It readily can be seen from Table II that excellent biodegradable detergents can be prepared from the hereinabove described isomerized Type III olefins of a straight chain structure as evidenced by the fact that after an 11 day period at least 96.5 percent of the detergent had disappeared from the solution.

By virtue of the present invention, there is thus provided an efficient process for utilizing C C Type III olefins for preparing C C alkylated benzenes and C C alkylated lower molecular weight aromatic compounds of the benzene series.

We claim:

1. In a process for preparing C C alkylated aromatic compounds from a Type III olefin of the formula (a) catalytically isomerizing said Type III olefins to shift the terminal double bond to an internal position in the presence of silica alumina, and

(b) alkylating said benzene with the isomerized product of (a) in the presence of said aluminum chloride alkylation catalyst to produce said C -C alkylated benzene.

5. A process according to claim 4 wherein said Type III olefins are catalytically isomerized in the presence of silica alumina at a temperature ranging from about room temperature to about 200 C. and wherein said silica alumina is present in an amount ranging from about 1 to about 20 weight percent based on the weight of said Type III olefins.

6. In a process for preparing C C alkylated benzene from a Type III olefin of the formula C=CH2 R R wherein R and R each are alkyl radicals having 1 to 10 R 2 carbon atoms, wherein the sum of the carbon atoms in R and R is in the range of 8 to 14 and wherein said Type III olefins are reacted with a low molecular weight aromatic compound of the benzene series in the presence of an acidic alkylation catalyst, wherein at least a portion of said Type III olefins dimerize prior to alkylation, the improvement which comprises obtaining improved yields of said C -C alkylated aromatic compounds by (a) catalytically isomerizing said Type III olefins to shift the terminal double bond to an internal position, and (b) alkylating said aromatic compound with the isomerized product of (a) in the presence of said alkylawherein R and R each are straight chain alkyl radicals having 1 to 10 carbon atoms, wherein the sum of the carbon atoms in R and R is in the range of 8 to 14 and wherein said Type III olefins are reacted with benzene in the presence of aluminum chloride alkylation catalyst wherein at least a portion of said Type III olefins dimerize prior to alkylation, the improvement which comprises obtaining improved yields of said C -C alkylated benzene by (a) catalytically isomerizing said Type III olefins to shift the terminal double bond to an internal position in the presence of silica alumina at temperation catalyst to produce said C -C alkylated arotures ranging from about 50 C. to about 100 C. matic compounds. wherein said silica alumina is present in an amount 2. The process according to claim I wherein said Type ranging from about 5 to about 10 weight percent III olefins are catalytically isomerized in the presence of based on the weight of said Type III olefin, and silica alumina. (b) alkylating said benzene with the isomerized prod- 3. The process according to claim 1 wherein said acidic uct of (a) in the presence of said aluminum chloride alkylation catalyst is aluminum chloride. alkylation catalyst to produce said C C alkylated 4. In a process for preparing C C alkylated benzene benzene. from a Type III olefin of the formula References Cited R\ 6r UNITED STATES PATENTS o=c1zn 3,104,269 9/1963 Schaffel 260683.2X 3,169,987 2/1965 Bloch 260671 X wherein R and R each are straight chain alkyl radicals having 1 to 10 carbon atoms, wherein the sum of the carbon atoms in R and R is in the range of 8 to 14 and DELBERT E. GANTZ, Primary Examiner. C. R. DAVIS, Assistant Examiner. 

